A motor vehicle with electric propulsion has two major drawbacks: its lower range than a heat engine vehicle of the same category and the significant time it takes to charge its traction battery.
The solution currently used to remedy these two drawbacks consists in equipping the motor vehicle with a range extender which for example takes the form of an additional battery, a small internal combustion engine or a fuel cell.
Such a range extender is for example presented in the document WO2013167267.
This autonomy extender operates with an optimum efficiency at a given temperature, which is generally different from that to which the other electrical components of the vehicle have to be cooled. A specific cooling circuit is then generally provided to cool the range extender.
This range extender is likely to be used in any situation. It is in effect generally controlled in such a way that as soon as the state of charge of the traction battery passes below a predetermined charge threshold (for example 20%), the range extender is used to supply the electric motor and/or the traction battery with current.
This situation can therefore occur in situations of extreme heat, notably when the vehicle is immobilized in a traffic jam and the outside temperature is very high.
Difficulties ensue for cooling the range extender to the temperature at which it exhibits an optimum efficiency (notably when the range extender is used at its nominal power).
The solution currently used when the cooling circuit is no longer able to sufficiently cool the range extender consists in reducing the electrical power delivered by this range extender, such that it generates less heat and the cooling circuit can keep its temperature at the optimum temperature.
It will be understood that this solution is not satisfactory because it generates a significant reduction in the performance levels of the motor vehicle when the heat conditions are limiting.